Building SOA-based Solutions for IBM System i Platform

22 Building SOA-based Solutions for IBM System i Platform

3.4 Web services description: WSDL

A WSDL document describes a Web service: Web service location, methods, and method

parameters. Example 3-4 shows a sample JavaBean implementation. Notice that this Web

service has one method convertTemp that has an input String parameter and output String

parameter.

Example 3-4 Sample JavaBean implementation

public class TempConversionService {

public String convertTemp(String tempIn){

Double tempFahrenheit = new Double(tempIn);

// Convert temperature

Double tempCelsius = new Double ((5/9)*(tempFahrenheit.doubleValue()-32));

// Return a String value

return tempCelsius.toString();

}

}

Example 3-5 shows a WSDL file that the WebSphere Development Studio client for iSeries

Web services wizard generated for this JavaBean. While the document can seem

complicated at a first glance, you can still see familiar elements from the Web service

implementation: Web service method name and parameter definitions. At the end of the

document you find the following Web services location:

<wsdlsoap:address location=

"http://localhost:9080/SimpleWS/services/TempConversionService"/>

Notice that the generated URL points to localhost. This URL is the only part of the WSDL

document that you need to change before deploying the Web service to the server and

sending WSDL to the Web service client developer. You need to replace localhost and the

default port with the host name of your server and WebSphere Application Server port.

Example 3-5 Sample WSDL file

<?xml version="1.0" encoding="UTF-8"?>

<wsdl:definitions targetNamespace="http://services.ibm.com"

xmlns:impl="http://services.ibm.com" xmlns:intf="http://services.ibm.com"

xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/"

xmlns:wsdlsoap="http://schemas.xmlsoap.org/wsdl/soap/"

xmlns:wsi="http://ws-i.org/profiles/basic/1.1/xsd"

xmlns:xsd="http://www.w3.org/2001/XMLSchema">

<wsdl:types>

<schema targetNamespace="http://services.ibm.com"

xmlns="http://www.w3.org/2001/XMLSchema" xmlns:impl="http://services.ibm.com"

xmlns:intf="http://services.ibm.com" xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/"

xmlns:xsd="http://www.w3.org/2001/XMLSchema">

<element name="convertTempResponse">

<complexType>

<sequence>

<element name="convertTempReturn" nillable="true" type="xsd:string"/>

</sequence>

</complexType>

</element>

Chapter 3. Web services technology stack 23

<element name="convertTemp">

<complexType>

<sequence>

<element name="tempIn" nillable="true" type="xsd:string"/>

</sequence>

</complexType>

</element>

</schema>

</wsdl:types>

<wsdl:message name="convertTempRequest">

<wsdl:part element="impl:convertTemp" name="parameters"/>

</wsdl:message>

<wsdl:message name="convertTempResponse">

<wsdl:part element="impl:convertTempResponse" name="parameters"/>

</wsdl:message>

<wsdl:portType name="TempConversionService">

<wsdl:operation name="convertTemp">

<wsdl:input message="impl:convertTempRequest" name="convertTempRequest"/>

<wsdl:output message="impl:convertTempResponse"

name="convertTempResponse"/>

</wsdl:operation>

</wsdl:portType>

<wsdl:binding name="TempConversionServiceSoapBinding"

type="impl:TempConversionService">

<wsdlsoap:binding style="document"

transport="http://schemas.xmlsoap.org/soap/http"/>

<wsdl:operation name="convertTemp">

<wsdlsoap:operation soapAction=""/>

<wsdl:input name="convertTempRequest">

<wsdlsoap:body use="literal"/>

</wsdl:input>

<wsdl:output name="convertTempResponse">

<wsdlsoap:body use="literal"/>

</wsdl:output>

</wsdl:operation>

</wsdl:binding>

<wsdl:service name="TempConversionServiceService">

<wsdl:port binding="impl:TempConversionServiceSoapBinding"

name="TempConversionService">

<wsdlsoap:address

location="http://localhost:9080/SimpleWS/services/TempConversionService"/>

</wsdl:port>

</wsdl:service>

</wsdl:definitions>

The WSDL file is sometimes called a

contract between a Web service and a Web service

client. After you create a contract, your goal should be not to introduce any changes to it.

Otherwise, the communication between a Web service client and a Web service will be

broken. You

can change Web service implementation (for example, change the way you

calculate temperature conversion). However, if you change your method of signature (method

name or parameter types), you will break the contract. Changing Web service location will not

break the contract. Just remember to notify the Web service client of Web service URI

change.